The data were collected using submerged paleoshorelines as strain markers to investigate Holocene and late Pleistocene vertical tectonic movement at the intersection of the offshore Santa Cruz– Catalina Ridge with the southern boundary of the Western Transverse Ranges, within the California Continental Borderland. Past submerged shoreline positions were identified using high-resolution multibeam bathymetry, side-scan sonar, submersible observations, and the presence of intertidal and subtidal invertebrate fossils.

Figure 1 (A) shows a map of the California Continental Borderland, offshore southern California, based on compiled multibeam data and (B) tectonic setting of the California Continental Borderland, which extends from Point Arguello to Cedros Island. Figure 2 shows (A) a simplified map of the major onshore and near-shore fault systems of the Los Angles basin and vicinity, showing the style of fault interactions at the boundary between the left-oblique and south-vergent thrusts that dominate the Transverse Ranges and right-lateral and right-oblique Peninsular Ranges oriented blocks and (B) a simplified map of the major offshore right-oblique fault systems of the northern California Continental Borderland and left-oblique and south-vergent thrusts that dominate the Western Transverse Ranges in the vicinity of the two blocks. Figure 3 is (A) high-resolution multibeam bathymetry of part of the Northern Channel Islands platform, focused on the southern and western sides of Santa Cruz Island and the southern side of Anacapa Island and (B) high-resolution multibeam bathymetry of the crest of the southern Santa Cruz–Catalina Ridge, with Pilgrim Banks to the north. Figure 4 shows locations of DELTA submersible dives made on the Northern Channel Islands platform and Santa Cruz–Catalina Ridge. Figure 5 is (A) map of identified slope breaks and terraces of the eastern Northern Channel Islands and (B) profile A–A′ crosses the central part of Santa Cruz Island, out to the platform edges. Figure 6 is a composite schematic diagram of paleoshoreline features observed during submersible dives on the Northern Channel Islands platform and Pilgrim Banks. Figure 7 shows (A) close-up of the bathymetry, NCI-S1 paleoshoreline, and terrace features on the southern Northern Channel Islands platform shelf edge between Santa Cruz and Anacapa Islands and (B) close-up of the bathymetry, NCI-S1 paleoshoreline, and terrace features on the southern Northern Channel Islands platform shelf edge near Bowen Point, south of Santa Cruz Island. Figure 8 is (A) a map of paleoshorelines and benches-terraces on Pilgrim Banks and (B) southeast-northwest profile (A–A′), showing the morphology of Pilgrim Banks in relation to several of the dated shell samples. Figure 9 shows linearly interpolated ice-equivalent eustatic sea-level curve for the late Pleistocene–Holocene epoch and Figure 10 is a preliminary map of geologic structures currently mapped using multichannel sparker, and recently released WesternGeco multichannel seismic-reflection profiles.